ETHREAL1 :
Hello,
I have a laptop with a 256GB msata and a 256GB SSD set up in RAID 1 and I want to change the SSD to a 1TB HDD and change it to RAID 0 without losing any data what do I need to do?
You want to make a RAID 0 array out of a 256Gb msata and a 1TB HDD for a total drive capacity of 1.25Gb? This would slow your SSD down and be pointless. I would not venture down this path. Additionally, do not put the SSD in a RAID configuration as you lose TRIM and will shorten the lifespan of the SSD/msata.
If you decide to go down the path you are headed, then you will need to:
1. Backup everything
2. Reinstall the OS
3. Restore everything
If you need additional storage I would use one of the 256gb as your primary/OS drive and get a fast 1Tb drive as storage. Not sure what you think you are getting by mixing. This will also save you a huge headache because you can just break your mirror (Raid 1) and add the new HDD as the second drive without any data loss.